Viconics VT8600 Series BACnet Integration Guide - Manual (Page 30)

VT8600 Series BACnet ® Integration Manual 30
Viconics Technologies Inc. | 9245 Langelier Blvd. | St.-Leonard | Quebec | Canada | H1P 3K9 | Tel: (514) 321-5660 | Fax: (514) 321-4150
028-0437-00 www.viconics.com | [email protected] March 2015
©
2
01
5 V
ic
onic
s T
ec
hno
lo
gi
es
Inc
. A
ll r
ig
ht
s r
ese
rv
ed
.
Note C)
Configuration Properties and User HMI objects.
Writing and binding to the priority arrays 4 to 16 property is a method to use IF the required intent is to lock
the local HMI and prevent local adjustments made by the user HMI values or the configuration property
values. If preventing the local user from accessing or tampering with the local HMI is the goal there are other
simpler and more elegant ways to do so:
• Proper selection of the user experience of the local HMI. AV2 / User HMI can tailor the user screen to
properly present to the user the only local adjustments allowed. In total 12 different HMI user screen
options are available. Locking the object by writing to array 4 to 16 is not required.
• AV56 / Main Password will prevent unauthorized installers from tampering with the configuration
properties. Locking the object by writing to array 4 to 16 is not required.
• AV57 / User Password will prevent unauthorized users from tampering with the user HMI value. Locking
the object by writing to array 4 to 16 is not required.
When writing and binding to the priority array 4 to 16, the control will NOT store and archive to flash memory
and will simply use it in RAM. As soon as the new present value is received in priority arrays 4 to 16, the con-
troller will use this new present value in all its internal control logics and functions.
When writing and binding to the priority array 4 to 16, the controller internal control logics and functions
ARE bypassed, and the controller will NOT operate with its own present values, but will be forced to use the
last write commands received on priority arrays 4 to 16 for its built-in internal control logics and functions.
HOWEVER, since these present values are only stored in RAM and not in flash, if a power reset occurs, the
override type function will be lost and the controller will start to operate using the relinquish default value. If the
override type function is required, a new write command to priority arrays 4 to 16 is needed.
The controller fully supports native and BACnet compliant priority array 1 to 16 write commands. This simply
means that a write value at level 4 has a higher authority than a write at level 9.
When writing and binding to priority array 4 to 16, a user cannot change user
HMI values and an installer cannot change configuration properties. In this case,
the present value used by the controller internal control logics and functions is
the last write command received at priority array 4 to 16.
You can easily identify an overridden point at the controller in either configuration
view, the setpoint view, the service view or the test outputs view. The point will
be highlighted in
RED indicating a write command to priority array 4 to 16.
The ONLY way to release the override due to the use of writing to priority array
4 to 16 is to send a write NULL command to the proper priority array currently
locking the controller.
New present value
process output based
on priority array 4 -16
Last
value
in
BACnet Relinquish
Default value
Local HMI
entered value
BACnet Priority
Array 4 to 16 value